Nanomagnetism, electronic structures & surfaces

For modern research on the nanoscale, like magnetoelectronics and spintronics, an understanding of the properties of complex materials in low dimensions is of prime importance. Vector-spin density functional theory provides a unique tool to investigate the electronic and magnetic properties in these systems. It allows to study the magnetic order, magnetization direction, ordering temperatures, transport properties, etc. of thin films, surfaces, and nanostructures.

( G. Bihlmayer)

Spintronics

The discovery of the giant- and tunnel magnetoresistance (GMR and TMR), i.e. the fact that the transport properties through an interface depend strongly on the magnetic properties of that interface, has revolutionized modern device technology. The quantum mechanical description of transport through an interface allows a detailed understanding of magnetic tunneljunctions used in spin- and magnetoelectronics. A basic concept in this description is the complex bandstructure shown here for Cu(100). It contains not only the "normal'' (Bloch) states of the solid (black), but also those "evanescent'' states (color) responsible for the transport process.

( D. Wortmann)

Electronic excitations, spindynamics

The principal way to gain knowledge about a material is to study its reaction to various external factors, such as light irradiation or magnetic fields. As the perturbation moves the system out of equilibrium, it serves foremost as a probe for excited states. A proper microscopic treatment of these processes is possible within many-body perturbation theory, which takes both the Coulomb interaction and the coupling to the external field explicitly into account. The theoretical simulations can thus be directly related to experimental spectroscopy and allow us to calculate electronic band structures or spin-wave spectra with great accuracy. Moreover, dynamic properties like the finite lifetime of elementary excitations are also accessible.

( A. Schindlmayr)